I'm getting E, which, according to the answer key, is not the OA.
I) whatever n is, (1-x^2) must be the opposite, i.e. if n is positive, then n^3 is positive and thus (1-x^2) must be a negative value. if n is negative, then n^3 is negative and thus (1-x^2) must be a positive value for its product to be less than 0. regardless, we don't know what x is because x^2 always produces a positive value. I) alone is not sufficient.
II) with x^2-1<0, it is implied that x must be a fraction. again, x could be either negative or positive given the fact that x^2 is always positive. II) alone is not sufficient either.
combining the two statements, we learn that x is a fraction less than 1, but it can be either negative or positive. thus, both statements together are not sufficient, no? am i missing something?
you can also work the inequalities...for I) by multiplying you have n^3-n^3x^2<0 which ultimately produces x^2>0. for II) you have x^2-1<0 which produces x^2<1. so we have 0<x^2<1 when combining the two statements. x must be a fraction, but could be either negative or positive.
Last edited by
bww on Mon May 14, 2007 6:32 am, edited 1 time in total.
